Vowel categorization by 3-year-old children

Abstract

A new two-alternative forced-choice procedure was used to assess perceptual constancy for vowel categories in 3-year-olds. The stimuli were edited natural tokens of /i/ and /a/ produced by male and female adults and male and female children. Subjects were visually reinforced for making an appropriate pointing response to one of two televisions. Initial training of the pointing response consisted of pairing an adult male /i/ with one television and an adult male /a/ with the other. After reaching an 80% correct criterion on the training stimuli, subjects were presented with blocks of eight stimuli (four /i/s and four /a/s). For subjects in the vowel group, all the /i/s were assigned to one pointing response, and all the /a/s to the other. For subjects in the arbitrary group, two /i/s and wo /a/s were assigned to each pointing response. The vowel group showed nearly perfect perceptual constancy for vowel categories by ignoring differences in speaker; the arbitrary group performed near chance. The success of this 2AFC pointing procedure will be discussed with respect to additional data on vowel normalization and identification of tokens from various synthetic continua.